1. Field of the Invention
The present invention relates to a control device for a power window or a sliding roof for an automotive vehicle, more particularly to such a control device that includes a function to prevent a foreign object from being pinched or sandwiched between a window frame and a sliding window glass.
2. Description of Related Art
A control device of this kind is disclosed in JP-Y2-2553373, for example. In this control device, a rotational speed variation rate of a motor that actuates a power window is calculated and stored in a memory. A predictive rotational speed is determined from the stored speed variation rate and a preceding rotational speed. If a presently detected rotational speed is lower than the predictive rotational speed, it is determined that a foreign object is pinched or sandwiched between a window frame and a sliding glass that is traveling in a direction to close the window. When such pinching is detected, the window glass is lowered to open the window.
The rotational speed of the motor, however, is affected by not only pinching but also other factors such as a terminal voltage of the motor and ambient temperature. Accordingly, the conventional control device in which detection of pinching solely depends on the predictive motor speed and the detected motor speed is not able to eliminate influence of other factors. Therefore, accuracy of the pinching detection is not sufficiently high. It may be possible to enhance the detection accuracy by storing data showing relation between the motor speed and other external factors in a microcomputer and modifying the motor speed based on the stored data. However, there is a problem that the control circuit becomes complex and a program size becomes large.